This invention relates to the detection of the overlapping of objects moving in a given path, and more particularly relates to method and apparatus for such detection employing one or more radiation sources for applying radiation to the surfaces of said objects and also employing detection means for receiving radiation reflected from the surfaces of said objects and detecting overlaps by shadows adjacent to an edge of one object which is overlapping another.
As the automatic transporting and processing of objects such as checks or currency in data processing systems and other types of systems has grown in recent years, the need has increased for a simple reliable means requiring minimal adjustment for detecting when one object, such as, for example, a check in a check sorting machine, or currency in an automatic money dispensing machine, has become overlapped with another, since such overlapping frequently produces undesirable results such as, for example, improper feeding of documents, or dispensing of an excessive amount of money from such devices as automated teller machines.
Examples of prior art double sheet detection systems are set forth in U.S. Pat. Nos. 3,278,754; 3,283,163 and 3,932,755.